VIXL contains three components.
The VIXL git repository can be found on ‘https://git.linaro.org’.
Changes from previous versions of VIXL can be found in the Changelog.
This software is covered by the licence described in the LICENCE file.
To build VIXL the following software is required:
A 64-bit host machine is required, implementing an LP64 data model. VIXL has been tested using GCC on AArch64 Debian, GCC and Clang on amd64 Ubuntu systems.
To run the linter and code formatting stages of the tests, the following software is also required:
Refer to the ‘Usage’ section for details.
The VIXL simulator supports only those instructions that the VIXL assembler can generate. The
doc directory contains a list of supported A64 instructions.
The VIXL simulator was developed to run on 64-bit amd64 platforms. Whilst it builds and mostly works for 32-bit x86 platforms, there are a number of floating-point operations which do not work correctly, and a number of tests fail as a result.
VIXL may not build using Clang 3.7, due to a compiler warning. A workaround is to disable conversion of warnings to errors, or to delete the offending
return statement reported and rebuild. This problem will be fixed in the next release.
Your project's build system must define
-DVIXL_DEBUG) when using a VIXL library that has been built with debug enabled.
Some classes defined in VIXL header files contain fields that are only present in debug builds, so if
VIXL_DEBUG is defined when the library is built, but not defined for the header files included in your project, you will see runtime failures.
All exclusive-access instructions are supported, but the simulator cannot accurately simulate their behaviour as described in the ARMv8 Architecture Reference Manual.
__sync_synchronize()is used for this purpose.
The simulator tries to be strict, and implements the following restrictions that the ARMv8 ARM allows:
Instructions affected by these limitations:
The helper script
tools/test.py will build and run every test that is provided with VIXL, in both release and debug mode. It is a useful script for verifying that all of VIXL's dependencies are in place and that VIXL is working as it should.
By default, the
tools/test.py script runs a linter to check that the source code conforms with the code style guide, and to detect several common errors that the compiler may not warn about. This is most useful for VIXL developers. The linter has the following dependencies:
cpplint.py, as provided by Google, must be available (and executable) on the
It is possible to tell
tools/test.py to skip the linter stage by passing
--nolint. This removes the dependency on
cpplint.py and Git. The
--nolint option is implied if the VIXL project is a snapshot (with no
tools/test.py tests code formatting using
clang-format-3.6. If you don't have
clang-format-3.6, disable the test using the
Also note that the tests for the tracing features depend upon external
sed tools. If these tools are not available in
PATH, these tests will fail.
We have separate guides for introducing VIXL, depending on what architecture you are targeting. A guide for working with AArch32 can be found here, while the AArch64 guide is here. Example source code is provided in the examples directory. You can build examples with either
scons aarch32_examples or
scons aarch64_examples from the root directory, or use
scons --help to get a detailed list of available build targets.